Vertebrate trackways from the Triassic Fremouw ...
From what can be seen, however, it is apparent that the collection contains at least the top portion of a skull, over 20 vertebrae, numerous ribs, portions of at least eight limb bones including a humerus and part of a femur, one side of a shoulder girdle, part of a pelvis and a number of pes elements. Excavation of the large fossils was accomplished with the aid of a gasoline-powered impact hammer/drill (see figure). In total, over 1,800 kilograms of fossil-bearing rock was removed from the site.
This research is supported by National Science Foundation grant DPP 88-17023 and the Augustana Research Foundation. Special thanks go to our colleagues David Elliot (Ohio State University) and Richard Hansen (Texas Christian University) for their discovery of the dinosaur site, and Larry Krissek (Ohio State) and Tim Homer (Ohio State University) for their sedimentological work. We would also like to acknowledge the excellent logistical support given by the Beardmore South Camp staff and Helicopters New Zealand.
References Barrett, P.J., R.J. Baillie, and E.H. Colbert. 1968. Triassic amphibian from Antarctica. Science, 161(3840), 460-462. Colbert, E.H. 1982. Triassic vertebrates in the Transantarctic Mountains. In M.D. Turner and J.F Splettstoesser (Eds.), Geology of the central Transantarctic Mountains. (Antarctic Research Series, Vol. 36.) Washington, D.C.: American Geophysical Union. Hammer, W.R. 1990. Triassic terrestrial vertebrate faunas of Antarctica.
In TN. and E.L. Taylor (Eds.), Antarctic paleobiology: Its role in the reconstruction of Gondwanaland. New York: Springer-Verlag.
Researchers use a gasoline-powered impact drill/hammer to excavate dinosaur fossils at the Mount Kirkpatrick site.
Vertebrate trackways from the Triassic Fremouw Formation, Queen Alexandra Range, Antarctica DAVID I.M. MACDONALD
British Antarctic Survey Natural Environment Research Council Cambridge CB3 0ET UK JOHN L. ISBELL
Byrd Polar Research Center and
Department of Geological Sciences Ohio State University Columbus, Ohio 43210 WILLIAM R. HAMMER
Department of Geology Augustana College Rock Island, Illinois 61201
20
Hammer, W.R., J.W. Collinson, and W.J. Ryan. 1990. A new Triassic vertebrate fauna from Antarctica and its depositional setting. Antarctic Science, 2(2), 163-169. Hammer, W.R., W.J. Ryan, and S.L. Defauw. 1987 Comments on the vertebrate fauna from the Fremouw Formation, Beardmore Glacier Region, Antarctica. Antarctic Journal of the U.S., 22(5), 32-33. Hammer, W.R., and J.W. Cosgriff. 1981. Myosaurus gracilis, an anomodont reptile from the Lower Triassic of Antarctica and South Africa. Journal of Paleontology, 55(2), 410-424.
During the 1990-1991 field season, a party of geologists from the British Antarctic Survey, Ohio State University, and Augustana College, discovered a Triassic vertebrate trackway in the Gordon Valley area of the Queen Alexandra Range (figure 1). This is the first Mesozoic vertebrate trackway to be found in Antarctica. The only other known vertebrate trace fossils are Oligocene-Miocene bird tracks, reported from the South Shetland Islands (Covacevich and Rich 1982). The trackway horizon occurs in a 167-meter-thick section of the middle and upper (basal part) members of the Fremouw Formation exposed along the north side of Gordon Valley (figure 2; cf. Barrett and Elliot 1973; Barrett, Elliot, and Lindsay 1986). A vertebrate bone bed was found near the top of this section in the 1985-1986 season (Hammer et al. 1986; Hammer, Ryan, and DeFauw 1987; Hammer, Collinson, and Ryan 1990). The trackways are at a stratigraphic height of 67 meters, in the middle Fremouw member. They occur on the top surface of a 65-centimeter-thick composite bed, which appears to be a silicified paleosol. The upper part of the bed comprises a 10centimeter massive layer with rootlets, overlain by a rubbly, nodular unit, which is in turn overlain by 2 centimeters of stylolitized chert, 5 centimeters of structureless siliceous mudstone, and 1 centimeter of laminated siliceous mudstone. These sedimentary rocks resemble a soil profile, which could either be a silicified calcrete (see examples in Collinson 1986) or an unusual style of silcrete. The structureless and laminated units at the top of the profile were probably deposited in an ephemeral lake. ANTARCTIC JOURNAL
Figure 1. Location map showing the trackway site (arrow) on the north side of Gordon Valley. Stippled areas are exposed rock or moraine. The tracks occur on the top surface of the laminated unit. They depress the bedding plane by 0.1-0.5 centimeter. Three different types are recognized (figure 3): • Type 1: These are the most common. Individual prints are 1.5-2 centimeters long, hemi-ovoid to triangular in outline. The two long sides are unequal in length, with smooth sharp outlines. The short side is straight-crenulate, displaying 1-4 cusps depending on the depth. One print has a long tail, deepening toward the most acute apex of the print. This is probably the mark of a foot being scuffed through the mud. Prints are 4-8 centimeters apart, and alternate about an unmarked center line, defining a trackway 2-2.5 centimeters wide. The trackways are straight at the scale of the exposure, and the longest set of prints found imply a repeat of about 25 centimeters. • Type 2: Several examples of this type were found. Individual prints are depressed, with five toes. Toes all face within an arc of about 130° and are deeply divided. Individual prints are 3-4 centimeters long and appear to be paired 10-20 centimeters apart with toes on opposite feet pointing out and forward of an (unmarked) center line. • Type 3: This type is represented by a single print 7 centimeters wide by 8 centimeters long. The print is poorly preserved with at least three toes. These are less deeply divided than those of type 2, and appear to be broader and more forward-facing. Tail marks are not associated with any of the types mentioned above, but smooth-edged, straight to gently curved indentations, 0.3-0.5 centimeters wide and up to 10 centimeters long, are common. They tend to be in groups with a near-random orientation. The tracks were probably made in soft mud on the site of a ephemeral pool. Variability of individual prints within any one type is a result of the depth of impression; this is a function of the consistency of the mud, the weight of the animal and the length of time that it stood in that spot. It would appear that the animal that made the type 1 tracks was small, narrow1991 REVIEW
Figure 2. Section through the Fremouw Formation at Gordon Valley showing the level of the trackway and of the main bone bed. The lowest 50 meters of unit A have been omitted for clarity. They are similar to the facies shown from 50-90 meters. (m denotes meter.) bodied, and moving purposefully. The type 2 animal was larger, heavier, and/or slower-moving. Identification of the animals which made the trackway will require careful matching with vertebrate remains from the Fremouw Formation. This work is underway, but preliminary examination suggests that the type 2 tracks may have been made by the mammallike reptile Lystrosaurus. This could be important, as the bone bed at Gordon Valley is probably in or above 21
the Cynognathus zone (Hammer et al. 1990). If the trackway did contain Lystrosaurus prints, the boundary between the Lystrosaurus and Cynognathus zones would lie in the 67-161-meter interval on the section. Continued work will assist the Triassic fossil zonation in the central Transantarctic Mountains. This research is supported by National Science Foundation grants DPP 89-17413 and DPP 88-17023, and by the British Antarctic Survey.
LAI :
References
\ A001A
Barrett, P.J., and D.H. Elliot. 1973. Reconnaissance geologic map of the
Buckley Island Quadrangle, Transantarctic Mountains, Antarctica
(U.S.Geological Survey Map A-3). Washington, D.C.: U.S. Government Printing Office. Barrett, P. 1 . , D. H. Elliot, and J. F. Lindsay. 1986. The Beacon Supergroup (Devonian-Triassic) and Ferrar Group (Jurassic) in the Beardmore Glacier area, Antarctica. In M.D. Turner and J.E Splettstoesser (Eds), Geology of the central Transantarctic Mountains. (Antarctic Research Series, Vol. 36) Washington, D.C.: American Geophysical Union. Covacevich, V., and P.V. Rich. 1982. New bird ichnites from Fildes Peninsula, King George Island, West Antarctica. In C. Craddock (Ed.), Antarctic geoscience. Madison: University of Wisconsin Press. Collinson, J.D. 1986. Alluvial sediments. In H.G. Reading (Ed.), Sedimentari,, environments and facies (2nd ed.). Oxford: Blackwell Scientific Publications. Hammer, WR., J.W. Collinson, and W.J. Ryan. 1990. A new vertebrate fauna from Antarctica and its depositional setting. Antarctic science, 2(2), 163-167 Hammer, W.R., W.J. Ryan, and S.L. DeFauw. 1987 Comments on the vertebrate fauna from the Fremouw Formation (Triassic), Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., 22(5), 32-33. Hammer, WR., W.J. Ryan, J.W. Tamplin, and S.L. DeFauw. 1986. New vertebrates from the Fremouw Formation (Triassic), Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., 21(5), 24-26.
:
• .* I ;
Figure 3. Photographs of the vertebrate tracks. Scales are in centimeters. A. Type 1 (arrows). B. Type 2. C. Type 3.
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This research is supported by National Science Foundation grant DPP 88-17023 and the Augustana Research Foundation. Special thanks go to our colleagues David Elliot (Ohio State University) and Richard Hansen (Texas Christian University) for their discovery of the dinosaur site, and Larry Krissek (Ohio State) and Tim Homer (Ohio State University) for their sedimentological work. We would also like to acknowledge the excellent logistical support given by the Beardmore South Camp staff and Helicopters New Zealand.
References Barrett, P.J., R.J. Baillie, and E.H. Colbert. 1968. Triassic amphibian from Antarctica. Science, 161(3840), 460-462. Colbert, E.H. 1982. Triassic vertebrates in the Transantarctic Mountains. In M.D. Turner and J.F Splettstoesser (Eds.), Geology of the central Transantarctic Mountains. (Antarctic Research Series, Vol. 36.) Washington, D.C.: American Geophysical Union. Hammer, W.R. 1990. Triassic terrestrial vertebrate faunas of Antarctica.
In TN. and E.L. Taylor (Eds.), Antarctic paleobiology: Its role in the reconstruction of Gondwanaland. New York: Springer-Verlag.
Researchers use a gasoline-powered impact drill/hammer to excavate dinosaur fossils at the Mount Kirkpatrick site.
Vertebrate trackways from the Triassic Fremouw Formation, Queen Alexandra Range, Antarctica DAVID I.M. MACDONALD
British Antarctic Survey Natural Environment Research Council Cambridge CB3 0ET UK JOHN L. ISBELL
Byrd Polar Research Center and
Department of Geological Sciences Ohio State University Columbus, Ohio 43210 WILLIAM R. HAMMER
Department of Geology Augustana College Rock Island, Illinois 61201
20
Hammer, W.R., J.W. Collinson, and W.J. Ryan. 1990. A new Triassic vertebrate fauna from Antarctica and its depositional setting. Antarctic Science, 2(2), 163-169. Hammer, W.R., W.J. Ryan, and S.L. Defauw. 1987 Comments on the vertebrate fauna from the Fremouw Formation, Beardmore Glacier Region, Antarctica. Antarctic Journal of the U.S., 22(5), 32-33. Hammer, W.R., and J.W. Cosgriff. 1981. Myosaurus gracilis, an anomodont reptile from the Lower Triassic of Antarctica and South Africa. Journal of Paleontology, 55(2), 410-424.
During the 1990-1991 field season, a party of geologists from the British Antarctic Survey, Ohio State University, and Augustana College, discovered a Triassic vertebrate trackway in the Gordon Valley area of the Queen Alexandra Range (figure 1). This is the first Mesozoic vertebrate trackway to be found in Antarctica. The only other known vertebrate trace fossils are Oligocene-Miocene bird tracks, reported from the South Shetland Islands (Covacevich and Rich 1982). The trackway horizon occurs in a 167-meter-thick section of the middle and upper (basal part) members of the Fremouw Formation exposed along the north side of Gordon Valley (figure 2; cf. Barrett and Elliot 1973; Barrett, Elliot, and Lindsay 1986). A vertebrate bone bed was found near the top of this section in the 1985-1986 season (Hammer et al. 1986; Hammer, Ryan, and DeFauw 1987; Hammer, Collinson, and Ryan 1990). The trackways are at a stratigraphic height of 67 meters, in the middle Fremouw member. They occur on the top surface of a 65-centimeter-thick composite bed, which appears to be a silicified paleosol. The upper part of the bed comprises a 10centimeter massive layer with rootlets, overlain by a rubbly, nodular unit, which is in turn overlain by 2 centimeters of stylolitized chert, 5 centimeters of structureless siliceous mudstone, and 1 centimeter of laminated siliceous mudstone. These sedimentary rocks resemble a soil profile, which could either be a silicified calcrete (see examples in Collinson 1986) or an unusual style of silcrete. The structureless and laminated units at the top of the profile were probably deposited in an ephemeral lake. ANTARCTIC JOURNAL
Figure 1. Location map showing the trackway site (arrow) on the north side of Gordon Valley. Stippled areas are exposed rock or moraine. The tracks occur on the top surface of the laminated unit. They depress the bedding plane by 0.1-0.5 centimeter. Three different types are recognized (figure 3): • Type 1: These are the most common. Individual prints are 1.5-2 centimeters long, hemi-ovoid to triangular in outline. The two long sides are unequal in length, with smooth sharp outlines. The short side is straight-crenulate, displaying 1-4 cusps depending on the depth. One print has a long tail, deepening toward the most acute apex of the print. This is probably the mark of a foot being scuffed through the mud. Prints are 4-8 centimeters apart, and alternate about an unmarked center line, defining a trackway 2-2.5 centimeters wide. The trackways are straight at the scale of the exposure, and the longest set of prints found imply a repeat of about 25 centimeters. • Type 2: Several examples of this type were found. Individual prints are depressed, with five toes. Toes all face within an arc of about 130° and are deeply divided. Individual prints are 3-4 centimeters long and appear to be paired 10-20 centimeters apart with toes on opposite feet pointing out and forward of an (unmarked) center line. • Type 3: This type is represented by a single print 7 centimeters wide by 8 centimeters long. The print is poorly preserved with at least three toes. These are less deeply divided than those of type 2, and appear to be broader and more forward-facing. Tail marks are not associated with any of the types mentioned above, but smooth-edged, straight to gently curved indentations, 0.3-0.5 centimeters wide and up to 10 centimeters long, are common. They tend to be in groups with a near-random orientation. The tracks were probably made in soft mud on the site of a ephemeral pool. Variability of individual prints within any one type is a result of the depth of impression; this is a function of the consistency of the mud, the weight of the animal and the length of time that it stood in that spot. It would appear that the animal that made the type 1 tracks was small, narrow1991 REVIEW
Figure 2. Section through the Fremouw Formation at Gordon Valley showing the level of the trackway and of the main bone bed. The lowest 50 meters of unit A have been omitted for clarity. They are similar to the facies shown from 50-90 meters. (m denotes meter.) bodied, and moving purposefully. The type 2 animal was larger, heavier, and/or slower-moving. Identification of the animals which made the trackway will require careful matching with vertebrate remains from the Fremouw Formation. This work is underway, but preliminary examination suggests that the type 2 tracks may have been made by the mammallike reptile Lystrosaurus. This could be important, as the bone bed at Gordon Valley is probably in or above 21
the Cynognathus zone (Hammer et al. 1990). If the trackway did contain Lystrosaurus prints, the boundary between the Lystrosaurus and Cynognathus zones would lie in the 67-161-meter interval on the section. Continued work will assist the Triassic fossil zonation in the central Transantarctic Mountains. This research is supported by National Science Foundation grants DPP 89-17413 and DPP 88-17023, and by the British Antarctic Survey.
LAI :
References
\ A001A
Barrett, P.J., and D.H. Elliot. 1973. Reconnaissance geologic map of the
Buckley Island Quadrangle, Transantarctic Mountains, Antarctica
(U.S.Geological Survey Map A-3). Washington, D.C.: U.S. Government Printing Office. Barrett, P. 1 . , D. H. Elliot, and J. F. Lindsay. 1986. The Beacon Supergroup (Devonian-Triassic) and Ferrar Group (Jurassic) in the Beardmore Glacier area, Antarctica. In M.D. Turner and J.E Splettstoesser (Eds), Geology of the central Transantarctic Mountains. (Antarctic Research Series, Vol. 36) Washington, D.C.: American Geophysical Union. Covacevich, V., and P.V. Rich. 1982. New bird ichnites from Fildes Peninsula, King George Island, West Antarctica. In C. Craddock (Ed.), Antarctic geoscience. Madison: University of Wisconsin Press. Collinson, J.D. 1986. Alluvial sediments. In H.G. Reading (Ed.), Sedimentari,, environments and facies (2nd ed.). Oxford: Blackwell Scientific Publications. Hammer, WR., J.W. Collinson, and W.J. Ryan. 1990. A new vertebrate fauna from Antarctica and its depositional setting. Antarctic science, 2(2), 163-167 Hammer, W.R., W.J. Ryan, and S.L. DeFauw. 1987 Comments on the vertebrate fauna from the Fremouw Formation (Triassic), Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., 22(5), 32-33. Hammer, WR., W.J. Ryan, J.W. Tamplin, and S.L. DeFauw. 1986. New vertebrates from the Fremouw Formation (Triassic), Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., 21(5), 24-26.
:
• .* I ;
Figure 3. Photographs of the vertebrate tracks. Scales are in centimeters. A. Type 1 (arrows). B. Type 2. C. Type 3.
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